Check the listing for details. 4" to 3" Eccentric Duct Reducer, 1Pcs Galvanized Iron Ducting Connector. Condition: New. Listed at 18.94 USD. This eccentric duct reducer and increaser are used as a duct adapter for duct diameter changes in the ventilation system. Suitable for the HVAC system, bathroom exhaust, air-cooled hood, embedded fans, hood, roller dryer, chimney, dust collection system, etc.SpecificationColor: SilverMaterial: galvanized ironSize: 125 x 0.6 mm/4.9 x 0.02 inches (H*W)The outer diameter interface: 100 mm / 3.9 inches;75 mm/2.9 inchesPacking List: 1 pcs x Eccentric Air Duct ReducerAdvantages:1. Made of durable galvanized iron material, strong, waterproof, moisture-proof, wear-resistant, good toughness, strong pressure resistance, not easy to deform, can be used for a long time.2. Smooth interior surface can reduce the resistance of ventilation.